A comparative study of the gametophytes of eight Mexican species of the genus Blechnum (Blechnaceae) is described. Fertile plants for spore collection were obtained at different Mexican localities. The spores were sown in agar enriched with Thompson media and cultured at 2225 °C, with a light regime of 12 hours. Spores of all species are monolete, ellipsoidal to spheroidal, and nonchlorophyllous. Vittariatype germination occurred after 614 days followed by a 26celllong filament and Aspidiumtype prothallial development. Adult gametophytes are cordiformspatulate to cordiformreniform and have wide wings with numerous unicellular marginal and superficial hairs. Sporophytes developed only in B. occidentale and B. polypodioides.